The invention relates to method and apparatus for cooling a furnace configured for processing refractory composites. More specifically, the invention is directed to method and apparatus for cooling a furnace more rapidly than prior art methods.
Processing of refractory composites takes place at elevated temperatures. Such processing includes CVI/CVD deposition of a binding matrix within a fibrous preform structure, and heat treating refractory composites. According to prior practice, the furnace is allowed to cool statically under vacuum or back-filled with an inert gas such as nitrogen. Cooling the furnace to a low enough temperature wherein the furnace may be opened can take days according to this practice. In addition, cooling the furnace too rapidly or introducing a reactive gas, such as oxygen, can cause damage to the furnace or the refractory composites being processed in the furnace. Therefore, a method and apparatus is desired whereby the furnace and the refractory composites are cooled more rapidly and at a controlled pace without damage.
According to an aspect of the invention, a method is provided for cooling a furnace configured to process refractory composites, comprising the steps of: flowing a cooling gas in a closed circuit through the furnace, over the refractory composites disposed within the furnace, and over a cooling element disposed within the furnace. The method according to the invention may further comprise the step of flowing the cooling gas by natural convection. The method according to the invention may also further comprising the step of flowing the cooling gas by forced flow.
According to a further aspect of the invention, a furnace configured to process refractory composites and a cooling system therefor is provided, comprising: a furnace shell that defines a furnace volume; a heater disposed within the furnace shell; a cooling element disposed within the furnace shell; an inlet conduit connected to the furnace shell in fluid communication with the furnace volume; an outlet conduit connected to the furnace shell in fluid communication with the furnace volume; a cooling gas supply configured to selectively introduce a cooling gas into the furnace volume; and, a blower connected to the inlet conduit and the outlet conduit in fluid communication therewith, wherein activation of the blower causes cooling gas introduced into the furnace volume to flow through the blower, through the inlet conduit, over the cooling element, through the outlet conduit, and back to the blower in a closed circuit.
The invention includes various other aspects as presented by the detailed description that follows.